Chapter 5: Problem 43
Find a symbolic representation for \(f^{-1}(x).\) $$ f(x)=-2 x+10 $$
Short Answer
Expert verified
The inverse function is \(f^{-1}(x) = -\frac{x}{2} + 5\).
Step by step solution
01
Understanding the Function
We start with the function given as \(f(x) = -2x + 10\). Our goal is to find its inverse, \(f^{-1}(x)\). This means we want to find a function that, when composed with \(f(x)\), will return the input value, \(x\). Simply put, if \(y = f(x)\), then \(f^{-1}(y) = x\).
02
Switching Variables
To find the inverse function, we switch the roles of \(x\) and \(y\). So, we rewrite the function \(y = -2x + 10\) as \(x = -2y + 10\).
03
Solving for y
Now, solve the equation \(x = -2y + 10\) for \(y\). Start by isolating \(y\). 1. Subtract 10 from both sides: \(x - 10 = -2y\) 2. Divide every term by \(-2\): \(y = \frac{x - 10}{-2}\) This simplifies to: \(y = -\frac{x}{2} + 5\)
04
Expressing the Inverse Function
Now that \(y = -\frac{x}{2} + 5\), we restate this in function notation as the inverse function: \(f^{-1}(x) = -\frac{x}{2} + 5\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Composition
Function composition involves combining two functions in a specific order. This concept is essential in understanding inverse functions. For a function \(f(x)\) to have an inverse, i.e., \(f^{-1}(x)\), the composition \(f(f^{-1}(x))\) and \(f^{-1}(f(x))\) should return the original input \(x\).
- \(f(f^{-1}(x)) = x\): This means applying the inverse function first, then the original function gets us back to our starting point \(x\).
- \(f^{-1}(f(x)) = x\): This means starting with \(f(x)\) and then applying the inverse also gets back to the input \(x\).
Solving Equations
Solving equations is a fundamental skill in finding inverse functions. After switching the variables in a function, you will need to solve for the new output variable to identify the inverse function.
In the given exercise, we swap \(x\) and \(y\) in the function \(y = -2x + 10\), resulting in \(x = -2y + 10\). Now, solving for \(y\) looks like this:
In the given exercise, we swap \(x\) and \(y\) in the function \(y = -2x + 10\), resulting in \(x = -2y + 10\). Now, solving for \(y\) looks like this:
- Subtract 10 from both sides: \(x - 10 = -2y\).
- Then divide by \(-2\) to isolate \(y\): \(y = \frac{x - 10}{-2}\).
- This simplifies to the expression: \(y = -\frac{x}{2} + 5\).
Algebraic Manipulation
Algebraic manipulation is crucial for deriving inverse functions because it allows us to rearrange and solve equations efficiently. In our example, we begin with the equation \(x = -2y + 10\) and use simple algebraic techniques to isolate \(y\).
The main tools of algebraic manipulation involved in this exercise include:
The main tools of algebraic manipulation involved in this exercise include:
- Subtraction: Adjust the equation by moving terms across the equals sign, like subtracting 10 from both sides to maintain equation balance: \(x - 10 = -2y\).
- Division: Once subtraction is done, we divide by the coefficient of \(y\), which is \(-2\), to solve for \(y\): \(y = -\frac{x}{2} + 5\).